As Internet messaging is getting more and more important and mission-critical, security against casual and professional adversaries has become a key issue and success factor. Fortunately, there are a few well-established technologies and standards that can be used to secure messages sent over the Internet, such as OpenPGP and S/MIME. Additionally, there are complementary security technologies that have distinct uses, such as Web-based and gateway solutions, certified mail, delivery platforms, and protection for instant messaging. It is important to properly understand all of these technologies in order to correctly apply and use them in the field. Secure Messaging on the Internet offers a comprehensive treatment of the technologies that are available today to secure Internet messaging, in particular, it brings together all the relevant and critical information needed to properly understand and use OpenPGP-and S/MIME-compliant software. Ideal for network and security professionals, this easy-to-understand book provides a complete guide to the topic.